I just found this, and it’s marvelous!
* * * * * * * * * * * * * * * * * * * * * * * *
As soon as I could safely toddle
My parents handed me a Model;
My brisk and energetic pater
Provided the accelerator.
My mother, with her kindly gumption,
The function guiding my consumption;
And every week I had from her
A lovely new parameter,
With lots of little leads and lags
In pretty parabolic bags.
With optimistic expectations
I started on my explorations,
And swore to move without a swerve
Along my sinusoidal curve.
Alas! I knew how it would end:
I’ve mixed the cycle with the trend,
And fear that, growing daily skinnier,
I have at length become non-linear.
I wander glumly round the house
As though I were exogenous,
And hardly capable of feeling
The difference ‘tween floor and ceiling.
I scarcely now, a pallid ghost,
Can tell ex ante from ex post:
My thoughts are sadly inelastic,
My acts invariably stochastic.
— Sir Dennis H. Robertson
